Process for converting oils



March e, 1934. L. KIRSCQBRAUN 1,949,480

PROCESS FOR CONVERTING OILS Filed May 25. 192i Patented Mar. 6, 1934 PROCESS FOR CONVERTING OILS Lester Kirschbraun, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of South Dakota Application May 23, 1921, Serial No. 471,885

-\ 12 Claims.

This invention relates to improvements in process and apparatus for converting oils and n refers more particularly to a process for converting under heat and pressure comparatively high boiling point oils into oils of a lower boiling point,

approximating gasoline and the like. g

Among the salient objects of the invention are to provide a process in which the oil, after having been raised to a cracking temperature is slowly circulated through a vaporizing zone, and subjected to vaporization, the unvaporized residual and higher boiling pointfraotions are circulated through a secondary heating zone apart from the raw and reiiuxed oil; toprovide -a process in which the greaterportion of the liquid oil is converted into vapors; to provide a process in which the circulation in the vapor chamber is retarded, permitting an increased reaction in the vaporizing zone; to provide an apparatus for effecting this process.

In the drawing: Fig. 1 is a diagrammatic side elevational view y of the apparatus, partly in section.

Fig. 2 is a detail section on the line 2-2 oi.' Fig. 1, looking in the direction of the arrows.

Referring in detail to the drawing, the raw oil is introduced from any'convenient source through the inlet pipe 1 controlled by a valve 2 and is charged through the line 3-regu1ated by a valve 4 by means of a pump 5 to the heating tubes 6 -mounted in the furnace 7. The furnace has a lower chamber in which the heating tubes are mounted and an upper chamber 8 communicating therewith by means of the brick grating 9.

. The furnace is preferably heated by means of gas burner 10. The-oil, after being heated to a cracking temperature in the lower chamber 7 passes through the transfer line 11 to the vaporizing chamber 12. This vaporizing chamber has 4Q a series of top baiiles 13 and bottom baiiies 14 for retarding the circulation of the oil through the chamber and permitting an increased reaction due to the retardation of the passage of the oil therethrough. The upper baiiles 13 are hinged i5 upon stay rods 15 positioned centrally in the chamber. The upper bafiles are in two sections and are adapted to be swung toward the center when. it is desired to clean the chamber and swung outwardly in position against the stops :l0 16 when in-use. Each section of the upper baille is perforated to form a vapor aperture 17, which permits a free circulation of the vapors in the upper part of the chamber. The lower baiiles 14 have holes 18 cut therein for permitting a re- .5 stricted quantity of the oil to circulate directly along the bottom of the chamber. This prevents also the trapping of the oil behind one of the baille sections of the vaporizing chamber.

After slowly circulating over the bailies in the expansion or vaporizing chamber, the vapors re- 0 leased are drawn oif through the vapor line 19 and directed to the dephlegmator-20 while the residuum passes down into a header 21 through the tubes 22 and intol the header 23 from which it returns to the vaporizing chamber and recir- 65 culates therethrough with the incoming oil from the heating tubes. The heavier residual oil may be drawn offthrough the residuum line 24 controlled by a valve 25. The gases from the lower combustion chamber 7 pass up through the brick .70 grating 9 and over theresiduum circulating tubes 22 and pass oiT through the stack 26. The vapors, after being refiuxed in the dephlegmator 20 are directed to the condenser 27 throughlthe. line 28 and are collected as distillate in the receiving 75 tank 29 which has a pressure relief pipe 30 con# trolled by a valve ,31,A pressure gauge 32, liquid level gauge 33 and a liquid drawoi line 34 controlled by a valve 35. The reux from the dephlegmator is drawn oi through the line 36 regu- 30 lated by a throttle valve 37 and may be drawn off to storage or to other converting means through the line 38 regulated by a valve 39 or directed back to the charging line 3 through the connecting line 40 in which is interposed a Valve 41. 35

The feature of slowly circulating the heated oil through the vaporizing chamber and the recirculation of the unvaporized portion through the heating zone in a set of tubes permits an increased yield to vbe extracted from the oil and reduces somewhat the temperature to which the oil may be originally heated to produce sufficient conversion of the oil in the reacting chamber. By recirculating the residuum in this manner, it obviates, to a great extent, the extremes oi.' temperature which are usually necessitated in producing the proper conversion of the' oil, thereby isolating the carbon in the upper heating tubes where the temperature conditions are less severe.

The lower heating tubes may be kept practically 'carbon-free and the uppertubes 22 may be more easily drained of the heavier residual substance', due to the fact thaty the oil is not maintained at as high a temperature as that in the lower tubes 6.

The temperature ofthe residual oilwhich is'A recirculated is such as to be more suited to produce further conversion of such residual products without necessitating storing in the original oil the heat necessary to produce the complete conversion. y

The apertures in the lower baffles are of such size asto admit such a flow of oil as to preclude the possibility of the residuum recirculating tubes from going dry but not sufficient to flush out the carbon which is deposited and accumulates between the baiile sections, thereby minimizing the amount of carbon returned to the recirculating tubes.

The process is preferably 'operated continuously.

I claim as my invention:

1. A process for converting oils, consisting in raising the oil ta cracking temperature in the heating zone, permitting the vaporiz'ation of the oil by slowly circulating it through a Vaporizing chamber, drawing off the released vapors and subjecting them to a dephlegmating and condensingaction, recirculating the unvaporized portion through a cooler portion of the heating zone, and returning this retreated portion and introducing it to the vaporizing chamber independently from the incoming heated oil, returning the reiiux from the dephlegmating -zone to be retreated in the heating zone. n

2. A process-of cracking hydrocarbon oil, consisting in passing the oil through a heating coil wherein it is subjected to a converison temperature, in discharging the heated oil into an en-i larged conversion chamber, in retarding its passage through said conversion chamber, in passing the vapors issuing from said conversion chamber to a dephlegmator, in returning reflux condensate from the dephlegmator to said heating coil, in condensing the vapors issuing from the dephlegmator and in collecting the resulting distillate, in circulating the unvaporized oil from said conversion i chamber through an independent heating elementwherein it is subjected to a lower temperature than the oil in said coil and back to the conversion chamber, in continuously withdrawing carbon containing residual oil from said secondary heating element and in maintaining a superatmospheric pressure on the oil undergoing conversion.

3. A process for cracking hydrocarbons comprising passing the oil once only through a heating coil wherein it is raised yto a conversion temperature, discharging the ,heated oil into an enlarged conversion chamber, taking off vapors from said conversion chamber for dephlegmation and condensation, returning reflux condensate resulting from said dephlegmation directly to said heating coil, circulating unvaporized oil from said conversion chamber through a cooler portion of the heating zone than that in which said heating coil is positioned and back to said conversion chamber, and in heating the circulating unvaporized oil only by heating gases previously employed to heat the oil in said heating coil.

4. The improvement in the operation of externally heated pressure stills, which comprises subjecting a body of oil in a pressure still to a cracking temperature by cyclically circulating it over heating surfaces, refluxing the vapors given off therefrom, forcing refiux from the said reiiuxing operation through a separate cracking zone without admixture with oil from said body, discharging the cracked oil from the said separate cracking zone prior to separation of vapors therefrom into the said body of oil, and passing the heating gases for the pressure still in heat exchange with the oil in the said separate cracking zone before bringing them into heat exchange Withthe heating surfaces over which said body of oil is circulated, whereby the heat of the heating gases is absorbed flrst in the oil in the said separate cracking zone and thereafter in heating the said body of oil.

5. The improvement in the operation of pressure cracking stills in which a body of oil is circulated from a bulk supply tank through heating tubes and back to the bulk supply tank, which comprises passing the heating gases for the pressure still first in heat exchange with oil in separate heating tubes and then in heat exchange with the heating tubes through which oil is circulated from and back to the said bulk supply tank, and circulating an auxiliary supply of oil without substantial admixture with the oil from the said body of oil which is circulating from the bulk supply tank through heating tubes and back to the bulk supply tank, once only through the said separate heating tubes and thence directly into the bulk supply tank.

6. The improvement in the operation of pressure cracking stills in which a body of oil is circulated from a bulk supply tank through heating tubes and back to the bulk supply tank, which comprises passing the heating gases for the pressure still first in heat exchange with oil in separate heating tubes' and then in heat exchange with the oil in heating tubes through which oil is circulated from and back to the bulk supply tank, and circulating an auxiliary supply of oil without substantial admixture with the oil from said body of oil which is circulatingA from the bulk supply tank and heating tubes and back to the bulk supply tank through the said separate heating tubes and thence prior to separation of vapors therefrom into the bulk supply tank, the said auxiliary supply of oil including reflux from vapors given off from the body of oil in the bulk supply tank.

7. The improvement in the operation of pressure cracking stills in which a body of oil is circulated from a bulk supply tank through heating tubes back to the bulk supply tank, which comprises subjecting the vapors given off from the said body of oil in the bulk supply tank to a refluxing operation and circulating the reflux therefrom Without substantial admixture of oil from the said body of oil once only through separate heating tubes, and passing the heating gases for the pressure still first in heat exchange with the oil in the said separate heating tubes and then in heat exchange with the oil in the heating tubes through which oil is circulated from and back to the bulk supply tank, whereby the temperature of the heating gases is reduced by the heat absorbed by the oil inthe said separate heating tubes before the heating gases are brought in heat exchange with the oil circulating from and back to the body of oil in the bulk supply tank.

8. The improvement in the operation of pressure cracking stills in which a body of oil is ,circulated from a bulk supply tank through heat- 'and back to the bulk supply tank once only through the said separate heating tubes and thence directly into the bulk supply tank, said auxiliary supply of oil including reflux from vapors given off from the body of oil in the bulk supply tank and additional fresh oil admixed therewith.

9. The improvement in the operation of pressure cracking stills in which a body of oil is circulated from a bulk supply tank through heating tubes back to the bulk supply tank,which comprises subjecting the vapors given off from the said body of oil in the bulk supply tank to a refuxingv operation and circulating the reflux therefrom without substantial admixture of oil from the said body of oil once only through separate heating tubes and then directly into the bulk supply tank and passing the heating gases vfor the pressure still rst in heat exchange with the oil in the said separate heating tubes and then in heat exchange with the oil in lthe heating tubes through which oil is circulated from and back to the bulk supply tank, whereby the temperature of the heating gases is reduced by the heat absorbed by the oll in the said separate heating tubes before the heating gases are brought in heat exchange with the oil circulating from and back to the b ody of oil in the bulk supply tank.

10. The improvement in the operation of externally heated pressure stills, which comprises subjecting a body of oil in a pressure still to a cracking temperature by cyclically circulating it over heating surfaces, refluxing the vapors given off therefrom, passing reflux from the said reuxing operation through a separate cracking zone without admixture with oil from said body,

discharging the cracked oil from the said sepa-- in the said separate cracking zone and thereafter in heating the said body of oil.

ll. A process of cracking hydrocarbon oil, consisting in passing the oil through a heating coil wherein it is subjected to a conversion temperature, in discharging the heated oil into an enlarged conversion chamber from which no unvaporized oil returns to said coil, in passing the vapors issuing from said conversion chamber to a dephlegmator, in returning reflux condensate directly from the dephlegmator to said heating coil, in ycondensing the vapors issuing from the dephlegmator and in collecting the resulting distillate` in circulating the unvaporized oil from said conversion chamberthrough an independent heating element wherein it is subjected to a lower temperature than the oil in said coil solely by heating gases previously employed to heat the oil in said heating coil and back to the conversion chamber, and in maintaining a superatrnospheric pressure on the oil undergoing conversion.

12. The improvement in the operation of externally heated pressure stills which comprises subjecting a body of oil in a pressure still to a cracking temperature by circulating the oil from an enlarged conversion chamber through heating tubes back to the enlarged conversionchamber, taking off vapors from the enlarged conversion chamber, subjecting such vapors to reflux condensation, returning the reux condensate resulting from such reflux condensation directly and without passage through said enlarged conversion chamber to a separate heating coil, delivering the heated reflux condensate from said separate heating coil, prior to substantial separation of vapors therefrom into said body of oil, and subjecting the reflux condensate flowing through said separate heating coil to a higher temperature than the temperature to which the circulating body ofoil is subjected by passing the heating gases used in the process first over said separate heating coil.

LESTER KIRSCHBRAUN. 

